1
WB JEE 2018
MCQ (Single Correct Answer)
+1
-0.25
Change Language
Four equal charges of value + Q are placed at any four vertices of a regular hexagon of side 'a'. By suitably choosing the vertices, what can be maximum possible magnitude of electric field at the centre of the hexagon?
A
$${Q \over {4\pi {\varepsilon _0}{a^2}}}$$
B
$${{\sqrt 2 Q} \over {4\pi {\varepsilon _0}{a^2}}}$$
C
$${{\sqrt 3 Q} \over {4\pi {\varepsilon _0}{a^2}}}$$
D
$${{2Q} \over {4\pi {\varepsilon _0}{a^2}}}$$
2
WB JEE 2018
MCQ (Single Correct Answer)
+2
-0.5
Change Language
The bob of a pendulum of mass m, suspended by an inextensible string of length L as shown in the figure carries a small charge q. An infinite horizontal plane conductor with uniform surface charge density $$\sigma$$ is placed below it. What will be the time period of the pendulum for small amplitude oscillations?

WB JEE 2018 Physics - Electrostatics Question 25 English
A
$$2\pi \sqrt {{L \over {\left( {g - {{mq} \over {{\varepsilon _0}\sigma }}} \right)}}} $$
B
$$\sqrt {{L \over {\left( {g - {{mq\sigma } \over {{\varepsilon _0}}}} \right)}}} $$
C
$${1 \over {2\pi }}\sqrt {{L \over {\left( {g - {{q\sigma } \over {{\varepsilon _0}m}}} \right)}}} $$
D
$$2\pi \sqrt {{L \over {\left( {g - {{q\sigma } \over {{\varepsilon _0}m}}} \right)}}} $$
3
WB JEE 2017
MCQ (Single Correct Answer)
+1
-0.25
Change Language
A positive charge Q is situated at the centre of a cube. The electric flux through any face of the cube is (in SI units)
A
$${Q \over {6{\varepsilon _0}}}$$
B
$$4\pi Q$$
C
$${Q \over {4\pi {\varepsilon _0}}}$$
D
$${Q \over {6\pi {\varepsilon _0}}}$$
4
WB JEE 2017
MCQ (Single Correct Answer)
+1
-0.25
Change Language
A charge of 0.8 coulomb is divided into two charges Q1 and Q2. These are kept at a separation of 30 cm. The force on Q1 is maximum when
A
Q1 = Q2 = 0.4 C
B
Q1 $$ \approx $$ 0.8 C, Q2 negligible
C
Q1 negligible, Q2 $$\approx $$ 0.8 C
D
Q1 = 0.2 C, Q2 = 0.6 C
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